A switching arrangement for a telephone switching system having test and seizing circuits has been disclosed in West German Pat. No. 1 013 701. One of the functions of the test relay P shown therein is to sense an idle condition in one of the telephone lines and then to stop the selector motor. To do this, the test relay is so designed that it responds far more rapidly than other known electromechanical relays. The response circuit for this test relay P includes the seizing circuit of a rear-position switching component. In conventional switching arrangements, this seizing circuit comprises an electromechanical relay such as, for example, shown in West German Auslegeschrift No. 1 940 847. To achieve a minimum response time for the test relay, the seizing relays in the seizing circuit normally carry in the quiescent condition a secondary short-circuited winding, whereby, when the test and seizing circuit is closed, a relatively steeper current rise is achieved which results in a relatively short response time for the test relay.
In addition, the use of purely ohmic resistances as the testing resistance or impedance in the seizing circuit has likewise been disclosed in West German Pat. No. 1 173 538. The necessary switching functions in this seizing circuit are carried out by transistors.
Seizing circuits as disclosed in West German Pat. No. 1 173 538 exhibit an even steeper current rise upon turning on a test and seizing circuit than the seizing circuit described in West German Auslegeschrift 1 940 847. Although in the latter Auslegeschrift the seizing relay has a secondary winding which is short-circuited in the quiescent condition, the remaining inductance of the seizing relay still causes a certain delay in the current rise in the test and seizing circuit. Thus, although the response time of rapidly operating test relays can be further accelerated as described above, this creates the problem of contact bounce. This contact bounce occurs where, after a first closing, the test relay contacts open briefly one or more times before coming to rest. In the test relay contacts which stop the selector motor, this results in increased contact wear due to the particularly heavy current load across these contacts.